Device for releasing a film sheet adhering to the inner surface of the upper cassette portion of an x-ray film cassette

ABSTRACT

Apparatus for loading and unloading x-ray film cassettes of various sizes, using an air jet to release a sheet of film from a pivotally open upper cassette part, the air jet nozzle being carried by a lever arrangement such that the nozzle is moved upwardly with the upper cassette part as the latter moves to its open position.

TECHNICAL FIELD

The invention relates to a device for releasing a film sheet whichadheres to the inner surface of the upper cassette portion of an X-rayfilm cassette when said upper cassette portion is pivoted to its openposition, with the aid of air blown between the film sheet and the innersurface of the upper cassette portion.

BACKGROUND ART

A film-sheet releasing device of this type is known (DE-OS 30 00 760).The known device is associated with a slider provided in a cassetteunloading and reloading apparatus for aligning and positioning an X-rayfilm cassette in the cassette unloading and reloading station of theapparatus. The slider is located laterally above a transport belt bymeans of which an X-ray film cassette is transported from an input pointup to a final abutment in the unloading and reloading station. If anX-ray film cassette is present in the unloading and reloading station,it is brought into contact with a stationary abutment ledge opposite tothe slider when said slider moves laterally towards the X-ray filmcassette. The film-sheet releasing device consists of a number of probesin the form of blast tubes (air nozzles) which are arranged in theslider and extended pneumatically in the direction of the X-ray filmcassette after the upper cassette portion has been slightly pivoted toits open position starting from the cassette side facing the slider. Theblast tubes are moved below the marginal area of the slightly open uppercassette portion such that the blast air emitted by them can bedistributed between the lower side of the upper cassette portion and afilm sheet partially adhering to said lower side so that when the uppercassette portion is fully opened, the film sheet is not moved with itbut remains in the lower cassette portion.

The probes are distributed at regular intervals across the length of theslider their number is determined by the length of an X-ray filmcassette of maximum size.

Owing to the great number of probes each of which is associated with apneumatically controlled device consisting of a pressure cylinder and apiston guided therein and provided with the probe, the film-sheetreleasing device as a whole is very expensive and complicated.

DISCLOSURE OF THE INVENTION

It is the object of the invention to provide an inexpensive film-sheetreleasing device of simple construction which operates reliably andprecisely and which requires only one single air nozzle for releasing afilm sheet from the upper cassette portion of X-ray film cassettes ofvarious sizes.

In accordance with the invention this object is attained in that alinkage-type multiple-lever arrangement is hinged to a bar adapted foraligning and positioning X-ray film cassettes of different sizes, thelast member of said multiple-lever arrangement extending into the pathof movement of the upper cassette portion of the X-ray film cassetteswhen said upper portion is pivoted to its open position, and beingengaged and held by said upper cassette portion, in that themultiple-lever arrangement can be pivoted along when the upper cassetteportion is pivoted to its open position and in that the last membersupports an air nozzle whose air jet is directed approximatelytangentially past the front edge of a film sheet, seen in the inputdirection of the cassette, for releasing such film sheet if adhering tothe inner surface of the film-sheet support of the other cassetteportion.

According to a useful modification a linkage-type multiple-leverarrangement is hinged to at least one of two parallely guided barsmovable towards and away from each other respectively for positioningthe X-ray film cassette.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in further detail with reference toan embodiment illustrated in the drawings in which:

FIG. 1 shows a plan view of a cassette-positioning device consisting oftwo parallely guided bars which are movable towards and away from eachother respectively;

FIG. 2 shows a plan view of part of the positioning device according toFIG. 1 with a film-sheet releasing device hinged to each bar;

FIG. 3 shows a sectional view along line 11-11 of FIG. 2, illustratingthe film-sheet releasing device in various functional positions of thepivotable upper cassette portion in an X-ray film cassette of smallsize;

FIG. 4 shows a sectional view along line 11-11 in FIG. 2, illustratingthe film-sheet releasing device in various functional positions of thepivotable upper cassette portion in an X-ray film cassette of largesize; and

FIG. 5 shows a sectional view along line IV-IV in FIG. 4 illustratingthe film-sheet releasing device.

PREFERRED MODE OF CARRYING OUT THE INVENTION

The apparatus comprising the invention serves for the loading andunloading of x-ray film cassettes such as are shown at 19 and 190 in thedrawings, 19 being a smaller cassette and 190 being a larger one. Exceptfor size the two types of cassette are identical. Each has a lower partor portion 19a, 190a and an upper part 19c, 190c, the leading end of theupper part having an end surface 19h, 190h. Upper part 19c, 190c carriesan inner film sheet support, one of which is shown at 19i. Film is shownat 67, 68 and, as shown in FIG. 3, projects slightly beyond the end ofsupport 19i. The cassette shown in FIG. 3 has a hinge 19k at its rearend, by which the upper part 19c is hinged to the lower cassette part19a. The larger size cassette of FIG. 4 has a similar hinge constructionwhich is not visible in the drawings. It will be understood that thefilm tends to adhere to support 19i and the similar part in the largersize cassette, hence the need for means for separating the film fromthat support to facilitate removal of the film from the cassette.

In an apparatus 1 for unloading exposed film sheets from X-ray filmcassettes of different sizes and reloading the cassettes with unexposedfilm sheets, a device for positioning the X-ray film cassettes, loadedinto the device edgewise from the bottom of FIG. 1, is provided in thearea of the unloading and reloading station. This positioning devicecomprises two parallely guided bars 10 and 12 which are movable towardsand away from each other respectively above a transport belt 15 whichtransports an X-ray film cassette 19 from an input point to theunloading and reloading station. The transport belt 15 is placed aroundtwo shafts 14 one of which is driven.

As can be seen in particular from FIGS. 1 and 5 the bars 10 and 12,which serve as guide members are mounted by means of screws 17 to angleplates 11 and 13. Each angle plate 11 and 13 respectively is shiftablymounted by means of a bushing 11a and 13a respectively on a guide shaft16 held between two mounting angles 1f of the apparatus. At the ends ofthe bars 10 and 12 extending into the interior of the apparatus, guidegrooves 10a and 12a are provided by means of which the bars 10 and 12are additionally guided for sliding movement on guide rails 1b arrangedon a partition wall 1a of the apparatus. The numeral 1e denotes acassette-abutment ramp situated on the partition wall and the numeral 1dtwo cassette abutments mounted to said partition wall.

The bars 10 and 12 are operated by means of a symmetric leverarrangement situated between said bars and consisting of a two-arm lever6 centrally mounted for rotation about a stationary pin 6c. A firstlever arm 7 pointing to the right is hinged to one free lever end 6a anda second lever arm 8 pointing to the left is hinged to the other freelever end 6b. The free ends 7a and 8a of the two lever arms 7 and 8 arehinged to the angle plates 11 and 13 supporting the bars 10 and 12.

The numeral 2 denotes a drive motor screwed to a holding angle 1cprovided on the apparatus. The free end 4a of a portion 4 of a rodconsisting of two portions 4 and 5 movable relative to each other ishinged to a crank disk 2a seated on the motor shaft and rotatable to andfro in the direction of the arrows "A" and "B" by the motor. The otherfree end 5a of portion 5 of the rod directly engages the hinge betweenlever 6 and the lever arm 8 pointing towards the left.

In the area of each free end of the two bars 10 and 12 extending intothe interior of the apparatus, a hold-down lever 20 and 21 is mountedwhich can be pivoted into and out of the transport path of the X-rayfilm cassette.

X-ray film cassettes of various sizes are used. In the case of theembodiment shown, only an X-ray film cassette 19 of minimum size and anX-ray film cassette 190 of maximum size are shown. When an X-ray filmcassette 19, 190 is fed into the input slot of the apparatus, the frontedge of the cassette enters first and the cassette is transported fromthe input point to the unloading and reloading station. Motor 2 isswitched on via switch means not illustrated in detail as soon as thefront side of the cassette makes contact with one of the abutments 1d,the motor operating the symmetric lever arrangement 6, 7 and 8 by meansof the crank disk 2a, rotating in the direction "A" and the 4, rod 5hinged to it, causing the bars 10 and 12 to move towards each other fromthe initial position shown in dash-dotted lines in FIG. 1 until theymake contact with the cassette side walls so that the X-ray filmcassette is aligned and exactly positioned.

A multiple-lever arrangement 60, 61 and 62 whose end member 62 carriesan air nozzle 70 as will be described in detail further below, is hingedto at least one of the two bars 10, 12.

In the embodiment shown, the multiple-lever arrangement 60, 61 and 62 isprovided on both bars 10 and 12 (FIG. 2). For this purpose, a bushing 66(FIG. 5) is riveted to each of the angle plates 11 and 13 supporting thebars 10 and 12. Pins 65 are mounted for rotation in the bushings 66. Oneach of the pins 65 is pivoted, a vertically extending first lever arm60 which projects through a recess 10c, 12c of bars 10 and 12. A secondlever arm 61 is hinged to the free end 60b of each lever arm 60 (FIGS. 3and 4), and is held by the force of a tension spring 64 connected tolever 60, against an abutment 60a is which limits the counterclockwisemovement as seen in FIG. 3. Arm 61 extends parallel to the direction offeed of the cassette. The last member 62, which extends into the path ofmovement of the pivotable upper cassette portion 19c and 190crespectively when the bars 10 and 12 rest against the side walls of thecassette, is hinged to the free end 61b of the second lever arm. Member62 carries the air nozzle 70 and a tapered downwardly extending pin 62ariveted adjacent to said nozzle.

The second lever arm 61 and the last member 62 of each multiple-leverarrangement rest loosely on support means arranged on the two bars 10and 12. First angle portion 10d, 12d, provided with support surface 10f,12f, serve as a support means for the second lever arm 61. Second angleportions 10g, 12g, extending upwardly from members 10, 12, provided withsupport surfaces 10h, 12h (FIG. 3), serve as support means for the lastmember 62. Each of the first angle portions 10d and 12d comprises anupwardly extending, inclined guide sheet 10e and 12e cooperating with asensing pin 27 provided on the second lever arm 61 such that themultiple-lever arrangements assume a predefined initial position withrespect to the front end face 19h and 190h respectively of the uppercassette portion 19c and 190c respectively.

Operation

With a cassette 19, 190 centered in its functional position in theunloading and reloading station by means of bar members 10, 12, theupper cassette part 19c, 190c is pivoted by known means (not shown) tothe positions shown in dash-dotted lines in FIGS. 3 and 4. After initialupward movement the downwardly extending front end face 19h, 190h of theupper cassette part 19c, 190c engages and slides along pins 62a untilthe upper cassette part 19c, 190c contacts the lower surface of the lastmember 62. Further pivoting of the upper cassette part to its openposition rotates the multiple lever arrangement 60-62 about pin 65.During this movement, sensing pin 27, located on second lever arm 61,leaves the guides 10e, 12e of the supporting angles 10d, 12d so that themultiple lever arrangements are only held by pin 62a on the end face19h, 190h of the open cassette upper part 19c, 190c.

As shown in FIG. 3, air nozzle 70 is vertically shiftable andhorizontally rotatable in a holder 62b fixed tot he last member 62. Theend of nozzle 70 is canted toward end faces 19h, 190h of the uppercassette part 19c, 190c. The canting angle "α" is 5 to 50 degrees withrespect to the plane of film sheet 67c. As can be seen from FIG. 2, theend of air nozzle 70 is also directed inwardly int eh horizontaldirection by an angle "β" of about 20 to 40 degrees with respect to theinput direction of cassette 19, 190.

While the upper cassette portion 19c and 190c is being pivoted into theposition shown in dash-dotted lines air is blown through the air nozzle70 for a period of about 0.3 to 0.8 seconds. Air nozzle 70 is adjustedin the vertical direction so that its bent off portion is aligned withrespect to the support plane of film sheet 67, 68 in such manner that anair jet emitted from the nozzle is directed approximately tangentiallypast the front edge 67a, 68a of a film sheet still adhering to the innersurface of the film sheet support 19i of the upper cassette part. Byshifting the air nozzle 70 in the vertical direction, a position isdefined in which its bent-off portion is aligned with respect to thesupport plane of the film sheet 67 and 68 respectively such that an airjet emitted is directed approximately tangentially past the front edge67a and 68a respectively of a film sheet 67 and 68 respectively stilladhering to the inner surface of the film-sheet support 19i of the uppercassette portion 19c and 190c respectively.

Due to a difference in the pressure of the air at rest in the area abovethe film sheet front edge 67a, 68a which projects from film sheetsupport 19i, and the air moved at high speed across the front edge 67a,68a of the film sheet by the air jet, which air continues to flow belowthe film sheet, a directional force is obtained which acts on the upperside of the projecting film sheet in the downward direction. This causesthe front marginal area of the film sheet to separate in a downwarddirection. At that moment, part of the substantially slower air streamwhich surrounds the sharply directed air jet can reach the space betweenfilm sheet 67, 68 and film sheet support 19i, and there builds up an aircushion so that film sheet 67, 68 is rapidly and readily released fromfilm sheet support 19i located in the open upper cassette part 19c,190c, whereupon the sheet drops downwardly into lower cassette portion19a, 190a. Subsequently the exposed film sheet is withdrawn from thelower cassette portion and transported into a development station whilstan unexposed new film sheet is transported into the lower cassetteportion. After the upper cassette portion has been pivoted to its closedposition, the X-ray film cassette is removed from the apparatus. Asshown in FIG. 3 the hinge 19k of the pivotable upper cassette portion19c of an X-ray film cassette 19 of small size is located in the area ofthe pin 65 of the support for the multiple-lever arrangement. Owing tothe short length of the upper cassette portion 19c in this case, thespring-biased second lever arm 61, which is hinged to the upright firstlever arm 60 rests on the abutment 60a of the first lever arm 60 whenthe upper cassette portion is in its open position. The multiple-leverarrangement 60, 61 and 62 is only pivoted about pin 65, since theproximity of pin 65 and cassette hinge 19k requires only that theupright lever arm 60 pivot rearwardly at approximately the same angle asthe opening angle of upper cassette portion 19c.

FIG. 4 shows that the hinge (not illustrated) of the pivotable uppercassette portion 190c of an X-ray film cassette 190 of large size is farfrom pin 65. Owing to the great length of the upper cassette portion190c in this case, the second lever arm 61, hinged to the upright firstlever arm 60, is pivoted away from the abutment 60a of the first leverarm 60 in opposition to the force of tension spring 64 when the uppercassette portion is in its open position in this case so that thepivotal movement of the multiple-lever arrangement 60-62 takes placesubstantially about the hinge between the second lever arm 61 and theupright first lever 60. The upright first lever arm 60 only carries outa slightly rearwardly directed compensating pivotal movement about pin65.

Due to the linkage-type design of the multiple lever arrangement 60-62it is ensured that the last member 62 always contacts the pivotableupper cassette parts of various sizes and is held at the end faces ofthe upper cassette parts and pivoted by pivoting movement of said uppercassette parts moving to their open positions. As a result, air nozzle70 is in its functional position at any opening angle of the uppercassette parts, regardless of the length of the cassette.

We claim:
 1. In apparatus for loading and unloading x-ray film cassettesof the type having a lower part and an upper part, the latter beingraised to separate it from the lower part for loading and unloading,which apparatus utilizes air jet means to separate film from the raisedupper cassette part; the improvement comprising:means operated bymovement of said upper cassette part toward its raised position to movesaid air jet means along with said upper cassette part.
 2. Apparatusaccording to claim 1, said apparatus having parallel lateral edge guidemeans for positioning the cassette, said improvement furthercomprising:said means operated by movement of said upper cassette partcomprising a multiple lever arrangement mounted on said guide means,said lever arrangement comprising a first lever arm hinged to said guidemeans and extending upwardly, said first lever arm having an abutment, asecond lever arm hinged to said first lever arm, biasing means urgingsaid second lever arm against said abutment, and a third lever armhinged to said second lever arm, said third lever arm having a portionextending into the path of upward movement of said upper cassette part,said third lever arm having a projection for engaging the inner face ofsaid upper cassette part and carrying air jet means for releasing filmfrom said upper cassette part.
 3. Apparatus according to claim 2, saidimprovement further comprising:means for positioning said second leverarm to assure that it and said third lever arm assume predefined initialpositions with respect to the leading edge of a cassette, said means forpositioning comprising an upwardly inclined guide member and a sensingpin carried by said second lever arm for cooperation with said guidemember.
 4. Apparatus according to claim 1, said improvement furthercomprising:said means for moving said air jet means having an elementthat is contacted by a surface of said upper cassette part to accomplishsaid movement of said air jet means.
 5. Apparatus according to claim 4,said cassettes being hinged together at one end, said improvementfurther comprising:said means operated by movement of said uppercassette part comprising hinged means.
 6. Apparatus according to claim5, said improvement further comprising:said air jet means being carriedby said hinged means.
 7. Apparatus according to claim 6, said apparatushaving parallel lateral edge guide means movable toward and away fromeach other to position said cassette, said improvement furthercomprising:said hinged means being mounted on said edge guide means. 8.Apparatus according to claim 7, said improvement further comprising:saidhinged means comprising a multiple lever arrangement.
 9. Apparatusaccording to claim 8, said improvement further comprising:means biasingsaid hinged means toward the upper surface of said upper cassette part.10. Apparatus according to claim 9, said improvement furthercomprising:means defining a rest position for said hinged means and airjet means, said rest position being spaced above the upper surface of acassette being fed into and out of the apparatus.
 11. Apparatusaccording to claim 10, said improvement further comprising:said air jetmeans having a nozzle for directing an air jet downwardly andtangentially with respect to an edge of film adhering to said uppercassette part.
 12. Apparatus according to claim 11, said improvementfurther comprising:said nozzle also directing the air jet sideways anddiagonally with respect to the film.
 13. Apparatus according to claim12, said improvement further comprising:said air jet means beingpositioned to direct air at an angle of 5-50 degrees with respect to theplane of the film, and at an angle of 20-40 degrees horizontallysideways with respect to the direction of cassette input into theapparatus.